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Energy Resources and Energy Transfer Group 4 - Coggle Diagram
Energy Resources and Energy Transfer Group 4
energy transfer
energy transfer types
mechanically
chemical --> elastic
an object moving due to a force
heating
chemical--> thermal
energy transferred from a hotter to colder object
conduction
heat transfer through stationary matter by physical contact.
examples: good conductors-->metals. bad conductors--> air
heat conduction: heat transfer by molecular contact
convection
more energetic particles moving from the hotter to cooler regions and transferring energy as they do so.
temp rises, density of object decreases. temp lowers, density increases. -->hot water circles up and cold water circles down
convection currents--> how wind forms
radiation
transferring heat through waves
thermal radiation (infrared waves): all objects emit some thermal radiation. Matt black surfaces: best emitters & absorbers. Shiny, light/silver surfaces: worst emitters & absorbers.
heat loss
thermal insulators: poor conductors of heat, e.g. plastic, wood, air especially when trapped and stops moving, ceramics, vacuum flasks etc.
radiation
related to light waves and/or sound waves
electrically
conservation of energy
energy can be stored and transferred between stores and dissipated, but it cannot be created or destroyed. The total energy of a closed system has no net charge.
wasted energy: energy that isn't useful, mostly wasted from sound and heat
total energy input=useful energy output + wasted energy
sankey diagram: visual representation of the flow of energy in a device or process.
efficiency
efficiency itself has to unit; it's recorded in percentages. 2. unit for energy: joules (J)
efficiency= useful energy output / total energy output x100% = useful power / total power
0<efficiency<1
work and energy
work
transfer of energy
work done=energy transferred
unit for work don: joules (J), 1J=1Nm
when work is done, not all of it's transferred to kinetic energy. some of it's lost as heat, increasing the temp of an object & it's surroundings
factors that affect the amount of work done: force and distance.
work done= force x distance moved in direction of force(a.k.a. displacement), W= FS
friction
opposes movement
power
power=work done/time taken, P=W/t=E/t
1W=1J/s
energy
principle of conservation of energy
main point: the total energy before and after the conservation doesn't change
forms of energy
kinetic energy动能
energy due to motion
W=FS=ma·(v^2-u^2)/2a=mv^2·1/2-mu^2·1/2, so kinetic energy(J)=mv^2 ·1/2, J=1/2· kg· m/s^2
potential energy势能
energy due to changed position/shape/state
gravitational potential energy, N/kg or m/s^2, g.p.e.=weight x height=mgh. if there is no air resistance, g.p.e. can be totally transformed into k.e.
renewable energy: can be replaced or regenerated and will never run out, at least for a very long time.
wind energy
solar energy
hydroelectric energy
non-renewable energy: will eventually run out, once used they cannot be used for a second time.
fossil fuels (coal, oil, natural gas)
nuclear energy
geothermal energy
types of energy
kinetic energy
energy due to motion of a body
Ek=1/2 x mv^2
unit: joules
anything moving has kinetic energy in its energy stores
thermal energy
energy due to thermal vibrations of the atoms and molecules of the objects.
any object-->the hotter it is, the more energy it has in its store
hotter places with higher temperatures to colder places with lower temperatures.
chemical energy
anything that can relate energy is a chemical reaction, e.g. food fuels
energy stores in chemical bonds that can be released via reaction
gravitational potential energy
anything in a gravitational field (anything that can fall)
energy due to the position of a body
elastic potential energy
anything stretched
springs and rubber bands
electrostatic energy
energy due to the flow of electric charges
two charges that attract or repel each other
magnetic energy
due to electric charges in motion
two magnets that attract or repel each other
nuclear energy
energy stored in nucleus can be released via nuclear reactions
atomic nuclei releases energy from this store in nuclear reactions
light energy
energy in light waves
sound energy
energy due to the vibration of the medium particles caused by sound waves
